Angiogenesis is implicated in the pathogenesis of a variety of disorders which include solid tumors, intraocular neovascular syndromes such as proliferative retinopathies or age-related macular degeneration (AMD), rheumatoid arthritis, and psoriasis (Folkman, J., et al., J. Biol. Chem. 267 (1992) 10931-10934; Klagsbrun, M., et al., Annu. Rev. Physiol. 53 (1991) 217-239; and Garner, A., Vascular diseases, in: Pathobiology of ocular disease, A dynamic approach, Gamer, A., and Klintworth, G. K. (eds.), 2nd edition, Marcel Dekker, New York (1994), pp. 1625-1710).
Ranibizumab (trade name Lucentis®) is a monoclonal antibody fragment derived from the same parent murine antibody as bevacizumab (Avastin®). However, it has been affinity matured to provide stronger binding to VEGF-A (WO 98/45331). It is known that VEGF-A blocking may be related to some systemic toxicities, therefore ranibizumab is missing an Fc part to reduce the serum half live and consequently systemic toxicities. It is an anti-angiogenic agent that has been approved to treat the “wet” type of age-related macular degeneration (ARMD), a common form of age-related vision loss.
Corneal angiogenesis assays have shown that both ANG-1 and ANG-2 had similar effects, acting synergistically with VEGF to promote growth of new blood vessels. Asahara, T., et al., Circ. Res. 83 (1998) 233-40. The possibility that there was a dose-dependent endothelial response was raised by the observation that in vitro at high concentration, ANG-2 can also be pro-angiogenic (Kim, I., et al., Oncogene 19 (2000) 4549-52). At high concentration, ANG-2 acts as an apoptosis survival factor for endothelial cells during serum deprivation apoptosis through activation of Tie2 via PI-3 Kinase and Akt pathway (Kim, I., et al., Oncogene 19 (2000) 4549-52).
WO 2010/040508 A9 and WO 2011/117329 relate to bispecific anti-VEGF/anti-ANG-2 antibodies. WO 2008/132568 relates to fusion proteins binding to growth factors. WO 2009/136352 relates to anti-angiogenic compounds. WO 2009/080253 and WO 2011/117330 relates to bispecific bivalent antibody formats. WO 2010/069532 relates to Ang2 antibodies.
Ocular vascular diseases such as age related macular degeneration (ARMD) and diabetic retinopathy (DR) are due to abnormal choroidal or retinal neovascularization respectively. They are the leading causes of visual loss in industrialized nations. Since the retina consists of well-defined layers of neuronal, glial, and vascular elements, relatively small disturbances such as those seen in vascular proliferation or edema can lead to significant loss of visual function. Inherited retinal degenerations, such as Retinitis Pigmentosa (RP), are also associated with vascular abnormalities, such as arteriolar narrowing and vascular atrophy. They affect as many as 1 in 3500 individuals and are characterized by progressive night blindness, visual field loss, optic nerve atrophy, arteriolar attenuation, and central loss of vision often progressing to complete blindness.
Ischemic retinopathies are characterized by loss or dysfunction of the retinal vasculature which results in a reduction of blood flow and hypoxia. The retina responds to hypoxia by generating signals to grow new blood vessels, but these new vessels are usually fragile and disorganized. It is the growth of these abnormal new vessels that creates most of the threat to vision since they can leak, hemorrhage or lead to scarring that may end in retinal detachment. Current treatments for ischemic retinopathies seek to halt the growth of the pathological vessels but do not address the underlying ischemia that drives their growth. Furthermore, standard treatment for diabetic retinopathy, an ischemic retinopathy that affects millions, involves destruction of a portion of the retina with a laser in an attempt to stop new vessel growth and preserve central vision. Strategies have been employed to block the function of vascular endothelial growth factor (VEGF), a major promoter of vessel growth. In the short term, anti-VEGF therapy can improve vision, but it does not address the underlying ischemia and in fact may exacerbate this condition as it inhibits all vessel growth, including beneficial collaterals. There is also the serious concern of systemic exposure of these drugs in elderly and/or diabetic patients where new vessel growth may be required in ischemic brains, hearts or limbs.
Typically for ocular diseases via intravitreal application smaller antibody fragments like Fab or Fab(2) are often used as they have a low serum half-life and the risk of systemic toxicities is lower. However this smaller fragments typically have also lower intravitreal half-lifes (e.g. due to the faster diffusion into serum) and have to be dosed typically more often.
Kim et al, Molecular Vision, 15 (2009) 2803-2812 relates to full length antibodies administered intravitreally in the eye, wherein an IgG with FcRn binding was eliminated into the blood in wild-type mice, whereas an IgY with no FcRn binding was not eliminated into the blood system. Furthermore the IgG with FcRn binding was not eliminated into the blood system in FcRn knockdown-mice.
There is a need in the art for better means for treating and preventing various ocular vascular diseases such as ischemic retinopathies.